In addition to macro definitions in the global environment,
any local macro definitions established within env by macrolet
or symbol-macrolet are considered.
If only form is supplied as an argument,
then the environment is effectively null, and only global macro definitions
as established by defmacro are considered.
Macro definitions are shadowed by local function definitions.

See cl:macroexpand and cl:macroexpand-1
in implementation.htm
for information on the implementation of macroexpand and macroexpand-1. Note
the links are to the documentation for the current Allegro CL
version. Replace /current/ in the URL with the Allegro CL version
number to see similar documentation is earlier releases.